Gyroscopes are used to measure the rate at which objects rotate. The information provided by gyroscopes can be used in many applications. For example, the information provided by gyroscopes can be used to trigger automobile airbags during rollover, improve the accuracy and reliability of GPS/navigation systems, and stabilize moving platforms such as automobiles, airplanes, robots, antennas, and industrial equipment.
A surface micromachined gyroscope typically includes various planar structures suspended with anchors and flexures over and parallel to an underlying substrate. Vibratory structures are typically dithered substantially along a dither axis in a plane parallel to the substrate and perpendicular to a sensitive axis that can be in the plane of the body or perpendicular to the planar structures and to the substrate. As is generally known, rotation of the gyroscope about the sensitive axis causes the planar structures move along a Coriolis axis, which is mutually orthogonal to the dither axis and the sensitive axis. This motion can be sensed to derive a signal that indicates the angular velocity of the rotation.